Electric furnace cooling system



Dec. 6, 1949 H. A. STRICKLAND, JR 2,490,105

ELECTRIC FURNACE COOLING SYSTEM Original Filed March 21, 1941 3 Sheets-Sheet l INVENTOR HAROLD A. STRICKLANDJR ATTORNEY H. A. STRICKLAND JR ELECTRIC FURNACE COOLING SYSTEM 3 Sheets-Sheet 2 Original Filed March 21, 1941 FIGJL INVENTOR HAROLD A. STRKCKLAND, JR.

ATTORNEY Dec. 6, 1949 H. A. STRICKLAND, JR 2,490,105

ELECTRIC FURNACE COOLING SYSTEM Original Filed March 21, 1941 3 Sheets-Sheet 5 1. d w m H ANN w m U M v A m N m T 1 m w A .I! R a w m 5 Q p m mum A v. H B p 0% b8 .nw x3 4! 15).. 0 1w q a 4 A j SN mw QQN w @mw qg 3 mww v m3 o Rm QN NTM 3N SN NFN 3M, n W EN MMN Patented Dec. 6, 1949 2,490,105 ELECTRIC FURNACE COOLING SYSTEM Harold A. Strickland, Jr., by mesne assignments,

Company, Cleveland, Ohio Detroit, Mich., assignor, to The Ohio Crankshaft Ohio, a corporation of Original application March 21, 1941, Serial No.

384,503, new

Patent No. 2,408,350, dated September 24, 194.6. Divided and this application July 4, 1945, Serial No. 603,197

18 Claims.

This invention relates to furnaces for heating by electro-magnetic induction, and particularly to those which can be used or are intended for use in the heating of bar or billet stock for forging purposes.

This application is a division of my copending application Serial Number 384,503, filed March 21, 1941, now Patent No. 2,408,350, dated September 24, 1946, titled Electric furnace machine.

A primary object of the invention is to provide cooling means for the coil with appropriate control therefor. An object also is to provide cooling means for the coil load support or rails which permit use of wear sustaining material for these elements. Another object is to provide a cooling system for a furnace which is jointly susceptible to temperature and pressure conditions therein for controlling power to the furnace. An object also is to provide means for preventing air moisture deposition on the load track. Other objects will appear on consideration of the following description of the invention and of the drawing, in which Figure 1 is a side elevation of the machine with the heating coil and workpiece push out mechanism indicated in broken lines;

Figure 2 is a cross section through the upper coil section;

Figure 3 is a View showing the cooling conduits and associated switches;

Figure 4 is a view in part section of the push out mechanism; and

Figure 5 is a section through a heating coil furnace provided with modified cooling units.

Referring now to the drawings, and first to Figures 1 to 4, particularly Figures 1 and 2, it will be observed that I have made the frame and housing of the furnace machine 30 generally of L-shape as viewed in side elevation, and in form not unlike the operators switchboard of a manually-operated telephone system. This is to say that the frame and housing comprise a horizontal branch 3| having a horizontal table-like top 32, and a vertically extending portion 33.

An opening in the top 32 of the table-like portion 3! is closed by a cast foundation member 39 which mounts the heating coil 40. An opening in the lower section of the vertical portion 33 of frame 30 is closed by a backplate 42 which mounts the workpiece gauging and ejecting mechanism and the magnetic core of the coil. An opening in the upper section of the vertical portion 33 of the frame is made for the mounting of the signal and instrument board (not shown), and is closed by this board when it is in place. A front-plate 50 rising from the region of the foundation plate 39, coacts with the rear-plate 42 in supporting the hood 41. The front plate closes the otherwise open front end of the hood 41. The foundation plate 39, the coacting and surmounted back and front plates 42 and 50 (also castings preferably) and the hood 41 together constitute a housing unit individual to the heating coil 40 and its immediately appurtenant parts. The front plate 50 is provided with an opening through which the workpieces are fed to the furnace by projecting them axially of the coil 40. A hinged door 52 closes or shrouds this opening during the heating operation.

A bus bar system 53 is housed in the portion 3| of the housing 30 just below the foundation plate 39 and table-top 32. It is connected at 54 by suitable buses to a source of power through a contactor mounted in the cabinet (not shown) and by leads 55 extending vertically downward to the banks of condensers 56 which are mounted by porcelain insulators 51a on a system of rails 51 mounted transversely of the section 31 of the housing.

Stock-gauge and push-out mechanism designated 58 and shown as mounted on the backplate 42, is accommodated within the vertical portion 33, as clearly appears in Figure 1. The pedaloperated actuating device 59 of this mechanism is, however, located in the bottommost part of the front section 3| of the housing and connected to the mechanism 58 by a conduit 60. The conduit 60 is preferably an overlong rubber hydraulic tubing whereby device 59 may be removed for servicing without the necessity of removal of hydraulic fluid from the system.

Also housed within the vertically extending portion 33 of the housing 30 are the systems of watercooling connections and their appurtenances illustrated in Figure 3. There is room in the rear part of the housing 30 to house a power transformer. The lowermost part of the vertical section 33 houses the contactor and such connections as are needful to connect it to the source of power on the one hand, and directly or through a transformer to the buses on the other.

The heating coil 40 and the supports for the workpiece are of a special construction which appears in Figure 2. The coil 40 is comprised of hollow conductors 6| generally of square shape. Cooling water in sufficient volume to cool the coil 40 is passed through the hollow of this conductor, as will be more fully described hereinafter. Laid axially upon the exterior of coil 40 are segmental strips 69 of Micarta, Bakelite, or the like,

which together completely encase the outer periphery of the coil 40. These longitudinally extending insulating strips 69 are bound in place by overlapped turns of insulating tape, given a water and moisture-proof treatment, and baked.

Heat is prevented from being directly radiated from the red or white hot surfaces of a workpiece being heated to the coil it! by an annular lining of insulating firebrick 14. This lining of firebrick like the insulating outer covering 69 is comprised of longitudinally-laid segments. However, instead of conjoining the end edges and hermetically sealing them together by baked insulating compound, as in the instance of the bars 69, the individual segments 75 of this lining are spaced from each other by water-cooled work-supportin rails it so constructed as to hold them radially outwardly against the surface of mica cylinder 66. To this end the opposite side edges of the segments 75 of the insulating lining (preferably comprised of a high-grade insulating firebrick compound) are chamfered, the chamfer terminating in a slight jog, and the rails 76 are provided with welded-on sheet metal holding clips 79 having a branch extending on each side of the rail it at the angle of the chamfer whereby to lie flatly against the chamfer and within the depth of the jog. Suitable support means for the rails are provided as disclosed in the copending application above referred to.

Heating coil 48 with its workpiece supporting I appurtenances is mounted with its axis coincid ing with the generally horizontal axis A-A of the furnace machine, by supporting it from coil centering c-clamps 98 carried from and forming a part of pedestals 99 erectedupon and secured to the cast foundation plate 39 of the table-por .tion 32 of the housing. There are two (or more in case of large coils) of these coil-supporting pedestals 99 spaced apart an adjustable distance to support coils of a number of different axial lengths without relocation 'upOn the foundation plate 39.

The C-clamps es of these supporting pedestals are comprised of c-arms, as Fig. 2, forked at their lower ends we to straddle the lower portions of pedestals 99 and be pivoted at H35 on the opposite side of the vertical plane V--V from the body of the C-clamp. When the clamps 88 are in clamping position, their upper ends lill lie in the Vertical plane V-V, and are provided with a threaded adjusting stud H38, the head me of which lies toward the coil ie from the upper end I 91 with the axis of the stud in the vertical plane V-V.

Beyond the head I89 projects a reduced extension of the stud 598 on which is radially slidably mounted a bridge member H2 carrying at its opposite ends pads of insulating material lite. A spring HE! on the reduced section H2 and between head illll and bridge life presses the bridge toward the coil id to clamp it yieldingly, while a washer and cotter H! prevent the radially movable bridge from dropping from the reduced extension of the stud I88 when the clamp is released.

' Mounted on an adjustable arm M23, as shown fixedly although it may be adjustable, is magnetic core 97 comprised of an annular series of radially-extending, radially-tapering laminations, the details of which are no part of the present invention and are, therefore, not shown. Sufilce it to say, they are bound in place upon the support M3 or equivalent support by any suitable means such, for example, as the comclearly appears in '4 monly known interlocking tongue and groove device 45.

The push-out mechanism comprises a preferably though not necessarily water-cooled pushout rod 5 working axially back and forth within the tubular workpiece stock gauge and support 543. It will be noted by reference to Figure l that this rod is water cooled all the way to its tip it? by means of an internally-laid waterinjection tube M3 which enters its tubular body by way of an elbow I48 connected with its rear end through a coupling I49. This water dis charges through the main body of the rod Hi5, externally of the injection tube I45, through coupling M9, and through a hollow 58 in the .elbow H55 in advance of the threaded connection -55! of the injection tube M8 therewith. Thus the elbow member M8 provides both an inlet connection !52 and an outlet connection E53. The engaging tip Ml of the push-out rod M6 is made of heat-resisting metal or other such material, and is preferably removably secured to the end in a manner not shown, but well known in connection with welding electrode tips and the like.

Effective provision is made for Water-cooling of all parts whatsoever, such as heat in what otherwise would be an undue measure. This cooling is provided not only for the coil 45 and its work supporting rails 16 and the water-cooled push rod I46 (mention of the hollow conductors for water-cooling of which has already been made), but also for the iron core 91, the condenser banks 56, and any transformers which may be used. A coil of water-cooling tubing 2H (see Figure 3) is provided about the magnetic core 97 for the purpose of cooling this mass of laminated transformer iron. The internal annular cooling of the push-out M36, as shown in Figure 4, also aids in cooling the core 91. The coil 2!! is closely heat-coupled to the laminations ill and provided with appropriate inlets and outlets.

The water-cooling system at large is illustrated in diagrammatic form in Figure 3. Here we have shown a principal water inlet 2! 3 projected through a shut-off valve 2M and a large strainer 2h: to a general machine-distributing main ZIE extending by appropriate branches to all apparatus to be cooled. Main 2l6 is connected with the ingoing terminal of coil 40 at 2H, with the in-going termini of the rails 16 at 2l8, with the inlet to the cooling coil 2 of the magnetic core 9'! at 2H9, with the push-out rod I46 at 226, and with the watch-circulating inlets of the condenser banks at 22!. Similar such connections as those made to coil 40 and condensers 55 may be made for transformer coils where transformers are used. The outlet connections of these parts are for the coil 48 at 222, for the rails at v 223, for iron-core-cooling coil 2H at 224, for

push-out rod M6 at 225, and for the condenser banks at 226. These outlet connections connect in common to the drain connection 227. Inasmuch as electric potentials appear across several of these water ports, it is necessary to make water connections through electrically insulating water conductors. This is done, for instance, in the cases of the heating coil, coolin coil for laininations, individual capacitors, etc. However, in

connection with various of these instrumentalities, there are provided control and signal actuating devices intervened between the inlet main 2 I 5 and the drainage main 227, respectively. The inlet connection 2|! to coil 40 is made directly with the main H8, and the outlet connection is by way of a conduit 228 through thermostat connections 223 governing a control switch 230 and through a water-flow controlled switch 23l. The inlet connection 2 l8 to the work-supporting rail system 1'6 is not, as in the case of the coil 40, direct to mains 2H5, but by way of an electric or other water heater 232 and a branch 233 whereby the water reachin the rails is heated to a temperature such that moisture condensation or collection on the rail 16 is prevented, irrespective of the state of use of the furnace. A bypass 234 from the heated water line 233 to the rail 16 supplies water also to the cooling coil 2!! of the iron core 91. This coil may be supplied directly from main 2H5, if desired, but the connection illustrated is preferable. Similarly flow-controlled switches like 23 I and thermostatically controlled switches 230 may be utilized and are intended to be utilized in connection either with the condensers 56 or any other instrumentalities where it is desired to individualize indicator switch and machine control due to temperature or flow of water connected with such instrumentality. The switches 230 and 23I, as shown in the drawings, are extras available for use in the event of some damage to the switches 230 and 23l or available for connection with the outlet cooling water of the condensers 56. When connected, their function would be identical with the control switches 230, 23l. A pressure-operated switch 235 is connected through pressure diaphragm 236 with the mains 216 to indicate through its action the fact that cooling water is on the system. Drain opening I24 of the base plate 39 is connected to a separate drain 231 used to prevent possible back pressure from line 221 forcing water into the base pan.

The flow switch 23! serves to disconnect the supply of electrical energy to the heating coil in the event the flow of cooling water shall reach a dangerously low amount, for example as might occur by means of a stoppage or pluggag'e of the passages through the specific part of the equipment being cooled even though full pressure was being applied to the entrance side of that part. Similarly, the switch 235 serves to disconnect the supply of electrical energy to the heating coil in the event the water pressure should reach dangerously low levels such as might not afiect the flow through the flow switches in as sufficient an amount as to actuate them. The two switches used operate in conjunction and of mutual benefit to each other so as to insure, if anything should happen to the cooling Water supply, that the heating coil cannot be energized and thus, possibly irreparably damaged.

This ensemble of the water-cooling system is, as heretofore stated, installed appropriately within the vertically extending section 33 of the main housing 3! and is, for the most part, mounted upon the rear of the generally vertical partition wall 238 (Figure 3) which is extended downwardly near to the bottom of the casing and upon the side walls of this vertical section 33 in any suitable manner.

The electrical control system of the machine is responsive to the coolant temperature and flow conditions which effect the operation of the switches 230, 231, 235 and 236. Relays 239 are controlled by the thermostatically operated switches 230 and control switches 240 to maintain these switches closed so lon as the water temperature to which thermostatic switches 230 are responsive is below a dangerously high point. Relays 242a are controlled by the flow-controlled switches 23! and maintain the switches 243 closed when the flow of water is established in the cooling system. Switch 25! in the circuit 24! which includes switches 240 and 243 is normally closed, but this switch is opened and switch 244 in circuit 242 (which includes a timer 248) is closed upon energization of relay 243a by the closure of switch H4 in circuit 24I, the closure of switch H4 being effected by movement of collar !53 attached to push-out rod i 45 (Figure 4) rearwardly under the pressure exerted upon the tip I41 by the workpiece. A thermostatically controlled switch 230 controls the circuit to water heater 232 for the water used to cool rails 16.

The pressure-operated switch 235 places potential upon the main bus lines 245 and 245 of the control system. Switchboard signal lamps 241 are connected across the lead-in of the control bus line 245, 246 from the low-voltage alterhating-current source 248 in advance of the pressure control switch 235, across lines 245, 245 behind the pressure switch 235, in parallel with the water heater 232 and under control of the thermostatic switch 230, and in parallel with each of the several relays 239, 242a and 243a, respectively. Illumination of these lamps indicates that the associated switch or relay is in on condition. Relay 255 in circuit 24I controls switch 254 in circuit 242, insuring that current will flow in circuit 242 only in case switches 240 and 243 are closed in response to activation of relays 239 and 242a. Switch 253 is provided in branch circuit 24la of circuit 241 and is actuated to closed position on energization of relay 250. A relay 283 is provided in circuit 242 and controls operation of switch 285 to cause closure of that switch upon energization of relay 283, thereby closing the circuit through which high-frequency, high-power current is passed through the coil 40.

The operation of the cooling apparatus of the machine is as follows:

Water having been turned into the water circuits of Figure 3 in advance, water pressure switch 235, thermostatic switch 235 of the heater 232, and thermostatic and flow switches 23D and 23I associated with the remaining cooling fluid circuits are all closed and the various associated indicating lamps 247 are illumined, showing that they are closed. Should any one of these switches be opened due to the absence of the condition which actuates it, the associated lamp will be out, showing the operator where trouble may lie. Closure of these several switches results in the closure of the circuits of each of the associated relays 239 and 242a, and consequently of the circuit 241 and switches 253 and 254. When the load is inserted in the heating chamber of coil 40, closing switch H4, and the furnace door is closed, the switch 244 will be closed by energize.- tion of relay 243a, with the result that the circuit 242 will be closed to energize relay 283, close switch 286, and close the high-frequency circuit through the coil 48 to heat the workpiece. When the heat cycle is completed the timer 248 interrupts the power flow, and the contacts 240 and 243, which in series establish the continuity of the preliminary control line 24 I, will be opened.

The closure of switch 253 in branch circuit 24 I a by the relay 253 establishes closure of the branch circuit 24l2ia, thereby maintaining flow of current through this circuit after the switch 25| in circuit 24! is opened by insertion of the workpiece. If the flow of current through circuit Z li-2 l la is interrupted during the heating cycle due to opening of switches 240 or 2-83 in response to improper coolant temperature or flow conditions, this will cause switches 253 and 254 to be opened, thereby interrupting the heating cycle by deenergization of relay 283. It will then be impossible to restart the heating cycle without first removing the workpiece, for the switch 2M is maintained open by the energization of relay 245:: so long as the workpiece is in the machine, and the circuit 262 cannot be reestablished without closure of switch 25i in response to removal of the workpiece, followed by closure of the switch 25d by insertion of the next workpiece.

My invention is susceptible of many modifications of its various component parts and their coacting inter-relationships and organizations. For example, the heating coil itself may be variously modified. I show in Figure 5 one such modification in which the rails l6 comprise each two tubular devices welded together in the radial plane to give them greater radial depth and stiltness. The retaining clasps l5- and the 8B are in turn welded to the radially inner tubular sections. Cooling water is passed through both of the tubular sections. It ma be passed down one such tubular section and returned by the other, or it may be passed through them in parallel as may be desired (such connections not being shown). This organization of the work-supporting rails permits a greater depth of heat insulating se ments i and, of course, permits use of a larger diameter of coil relative to the diameter of the workpiece, (the latter shown in Figure 2 generally in dot-and-dash lines).

Throughout the specification I have used the term heating coil to apply to the electromagnetic inducing element to which the workpiece is juxtaposed to receive the electromagnetic induction. This term I wish broadly construed to comprehend electromagnetic inductor devices of all sorts irrespective of the shape and dimensions of the coil and indeed irrespective of whether or not a device has the form of a coil.

It is understood that the invention as described carries no limitation except as set out in the fol-- lowing claims.

What is claimed is:

i. A machine for heating workpieces by electromagnetic induction comprised of a heating coil, workpiece supporting rails juxtaposed thereto, and provided with means for cooling by circula tion of a cooling fluid, means for supplying cooling fluid to said first-named means at a temperature above that at which said rails will collect atmospheric moisture, and a power-circuit for supplying heating power to said heating coil,

which circuit is controlled by a thermostat responsive to the heat of the source of fluid supply for the rails, to prevent heating of the workpiece when the cooling fluid exceeds the proper ten perature.

2. A machine of the character described comprising an electro-magnetic induction heating coil having cooling fluid circuit, a source of power for the coil, and a control circuit including means for iterrupting said source of power dependent for its activation jointly upon the flow of cooling fluid and the maintenance of'the flowing cooling fluid below a predetermined temperature.

3. An apparatus for heating a workpiece by electromagnetic induction including an inducing coil, a track within said coil, a coolant passage to and through said track, means for moving coolant through said passage, a switch for the supply of power to said coil and means responsive to the how of coolant in said passage for actuating said switch to supply power to said coil only upon flow of coolant in said passage.

4. In an apparatus for heating a workpiece by electromagnetic induction, an inducing coil, a track within the coil along which a workpiece may be slid, passages for coolant circulation in said track, and means responsive to the temperature of the track coolant for maintaining a switch causing supply of power to said coil closed when the temperature of coolant is below a predetermined point and open when said temperature is exceeded.

5. An electromagnetic induction heating apparatus comprising a heating coil, means for supplying coolant through said coil, a switch for supplying high frequency currents to said coil, and flow controlled means responsive to a reduction in the flow of coolant through said coil for opening said switch and cutting on" the supply of power to said coil.

6. An apparatus for electromagnetic induction heating comprising a coil, a work supporting track extending longitudinally of the coil, means for supplying coolant to said coil and track, a switch for connecting said coil with a source of power, and means for opening said switch in response to either a reduction in coolant flow or to an increase in temperature of the coolant discharge from said coil and track.

7. An apparatus for heating a workpiece by cctroniagnetic induction comprising a heating il, means for supplying coolant through said cell, a switch for supplying electrical energy to said coil, means for opening said switch in response to a reduction of flow of coolant through said coil, and means for opening said switch in response to a reduction in coolant pressure for the coil.

3. An apparatus for heating a workpiece by electromagnetic induction comprising a heating coil, means for supplying coolant through said coil, a switch for supplying electrical energy to said coil, means for opening said switch in response to a reduction of flow of coolant through said coil, and means for opening said switch in response toa reduction in coolant pressure for the coil, said pressure means being responsive to pressure on the supply side of the coolant to said coil, and the flow means being responsive to the flow of coolant on the outlet side of the coil.

9. An apparatus for heating a workpiece by electromagnetic induction comprising a heating coil, means for passing coolant through the coil, a switch for supplying electrical energy to said coil, and means responsive to a reduction in the flow of coolant, an increase in coolant temperature, or a reduction in coolant pressure for opening said switch and cutting on the supply of ener y to said coil.

10. An apparatus for heating 'a workpiece by electromagnetic induction which comprises means controlling the supply of electrical energy to said apparatus, means for supplying coolant to said apparatus, and means responsive to a reduction in the flow of coolant to said apparatus to below a predetermined value for actuating said control means and cutting off the supply of electrical heating energy to the apparatus.

11. An apparatus for heating a workpiece by electromagnetic induction which comprises means controlling the supply of electrical energy to said appparatus, means for supplying coolant to said apparatus, and means responsive to both a reduction in the flow of coolant and an increase in the temperature of said coolant discharge from said apparatus for actuating said controlling means and cutting ofi the supply of electrical heating energy to said apparatus.

12. An apparatus for heating a workpiece by electromagnetic induction which comprises means controlling the supply of electrical energy to said apparatus, means for supplying coolant to said apparatus, and means responsive to both a reduction in the flow of coolant and a reduction in the pressure of coolant for said apparatus for actuating said controlling means and cutting off the supply of electrical heating energy to the apparatus.

13. An electromagnetic induction heating apparatus including a coil, a work supporting track extending along said coil, means for supplying a coolant to said track, and means for heating said track coolant to a temperature above that at which moisture may be deposited on the track from the atmosphere.

14. An electromagnetic induction heating apparatus comprising a heating coil, a core generally coaxial with a workpiece and adjacent an end thereof, a coolant passage for the core, a heater for the coolant supplied to the core and thermostatic means controlling the passage of coolant through said heater whereby the core coolant is supplied at a temperature above that at which moisture might be deposited from the atmosphere.

15. In heating apparatus having a heating chamber, a heat control means for the chamber, a track within the chamber for supporting a. workpiece therein, means for coolant circulation in said track, and means responsive to the temperature and pressure of said coolant for controlling the heat control means of said furnace.

16. A machine of the character described comprising an electromagnetic induction heating coil adapted to receive a workpiece and having cooling fluid circuit, a source of power for the coil,

10 and a control circuit including means for interrupting said source of power operable upon failure of flow of cooling fluid, and means for maintaining the interruption of said source of power until the workpiece is removed from said induction heating coil.

17. A machine of the character described comprising an electromagnetic induction heating coil adapted to receive a workpiece and having cooling fluid circuit, a source of power for the coil, and a control circuit including means for interrupting said source of power operable when the cooling fluid exceeds a predetermined temperature, and means for maintaining the interruption of said source of power until the workpiece is removed from said induction heating coil.

13. An apparatus for heating a workpiece by electromagnetic induction including an inducing coil, a track Within said coil, a cooling passage to and through said track, a coolant passage in said coil, means for moving coolant through said passages, a switch for the supply of power to said coil and means responsive to the pressure of the coolant entering said passages for actuating said switch to supply power to said coil only upon maintenance of pressure in said passages.

HAROLD A. STRICKLAND, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 451,240 Dewey Apr. 28, 1891 919,366 Lemp Apr. 27, 1909 1,614,620 Kittredge et a1 Jan. 18, 1927 1,691,349 Harrington et al. Nov. 13, 1928 2,091,219 Sciaky Aug. 24, 1937 2,281,335 Somes Apr. 28, 1942 2,321,189 Dravneek June 8, 1943 2,329,904 Howard Sept. 21, 1943 2,365,021 Strickland Dec. 12, 1944 2,408,350 Strickland Sept. 24, 1946 

